1. Field of the Invention
This invention relates to a photosensitive material discharging apparatus for transporting along a transport path and discharging a photosensitive material. More particularly, the invention relates to a photosensitive material discharging apparatus having a discharge section disposed downstream of a transport path for discharging a photosensitive material, a plurality of discharge roller pairs arranged in the discharge section for discharging the photosensitive material, and a plurality of transport roller pairs arranged on the transport path upstream of the discharge roller pairs.
2. Description of the Related Art
The above photosensitive material discharging apparatus is disclosed in U.S. Pat. No. 5,724,626, for example. The prior apparatus defines a transport path for transporting a photosensitive material emerging from a developing stage and a drying stage, to a loading conveyer for loading the material onto a sorter. This transport path includes a first transporting pinch roller mechanism having a plurality of pinch roller pairs, and a second transporting pinch roller mechanism disposed in an exit region of the transport path. The second pinch roller mechanism is capable of transporting the photosensitive material at a higher speed than the first pinch roller mechanism.
The pinch rollers constituting the first pinch roller mechanism are elongated rollers each extending perpendicular to a transport direction. The second pinch roller mechanism has large drive rollers, and small driven rollers opposed to the drive rollers, respectively. The drive rollers are mounted on roller shafts driven by a drive shaft through transmission gear mechanisms. Further, a torque limiter is disposed between a driven gear of each transmission gear mechanism and the roller shaft of each drive roller. The torque limiter is operable in response to a torque greater than a predetermined value to render the drive roller freely rotatable.
The photosensitive material introduced into this photosensitive material discharging apparatus is first transported by the first transporting pinch roller mechanism, at a transporting speed corresponding to a peripheral speed of the rollers of this roller mechanism, to a position adjacent an exit of the transport path. As the forward end of the photosensitive material advances into the second transporting pinch roller mechanism, the drive rollers of the second pinch roller mechanism would exert an effort to transport the material at a peripheral speed of the drive rollers. However, since the rear end of the photosensitive material is still engaged by the first transporting pinch roller mechanism, the torque limiters of the second transporting pinch roller mechanism operate to allow the photosensitive material to remain being transported at the transporting speed produced by the first transporting pinch roller mechanism. When the rear end of the photosensitive material is released from the first transporting pinch roller mechanism, the second transporting pinch roller mechanism accelerates the transport of the material to discharge it at high speed from the exit of the transport path.
The prior apparatus noted above has a disadvantage of requiring the torque limiters mounted in the second transporting pinch roller mechanism, which results in an increased cost. Moreover, where sheets of the photosensitive materials are discharged as a three-lane phase-staggered arrangement, the apparatus requires the number of torque limiters corresponding to the number of lanes. Then, the apparatus involves a very large cost. Where a plurality of torque limiters are used, variations among the torque limiters destabilize delivery of the sheets of the photosensitive material. This results in the sheets being discharged to varied, irregular positions.